Solve for $x$ and $y$ by deriving an expression for $x$ from the second equation, and substituting it back into the first equation. $\begin{align*}7x+7y &= 7 \\ x+2y &= -8\end{align*}$
Explanation: Begin by moving the $y$ -term in the second equation to the right side of the equation. $x = {-2y-8}$ Substitute this expression for $x$ in the first equation. $7({-2y - 8}) + 7y = 7$ $-14y - 56 + 7y = 7$ Simplify by combining terms, then solve for $y$ $-7y - 56 = 7$ $-7y = 63$ $y = -9$ Substitute $-9$ for $y$ in the top equation. $7x+7( -9) = 7$ $7x-63 = 7$ $7x = 70$ $x = 10$ The solution is $\enspace x = 10, \enspace y = -9$.